The present invention relates generally to vehicle structural systems, and more particularly to a structural attachment system having features for attaching components to one another within a vehicle, for providing reinforcement in load bearing areas of the components, and for allowing effective distribution of loads within the vehicle.
Typically, a steering assembly of a vehicle includes a steering column extending between a steering mechanism, for example, a steering wheel, and a torque distribution mechanism. The steering column is designed to translate rotation of the steering wheel by a vehicle operator to the torque distribution mechanism which correspondingly positions the wheels of the vehicle in accordance with the position of the steering wheel, thus steering the vehicle.
It is desired that the steering column be of a sufficient compressive, shear, and torsional strength to endure the above described usage. The steering column designed as such can have a substantial mass and thus must be properly supported within the vehicle for effective functioning of the vehicle steering assembly.
Accordingly, the steering column is supported by attachment to a cross-car structural beam located within the vehicle. The load resulting from the weight of the steering column and other loads encountered during vehicle usage are distributed through the cross-car structural beam to side walls of the vehicle and/or to other parts of the vehicle where the cross-car structural beam is mounted thereto. The weight of the steering column is thereby conveyed, through the side walls and/or other vehicle parts, to a steel frame of the vehicle. Other parts of the vehicle which lend to the structural support system include, for example, an engine wall, a front-of-dash, etc.
The cross-car structural beam is generally a load-bearing member that is also used to support an instrument panel assembly and a heating ventilation and air conditioning (HVAC) structural duct system, both located about the beam. The structural beam further serves as a reaction surface for occupant protection devices such as air bags or knee bolsters.
The steering column is typically attached to the cross-car structural beam directly or by a steering column support structure. The steering column support structure is composed of a metal or a composite and is attached at a first end to the cross-car structural beam and at a second end to the steering column.
The steering column support structure must support the load of the steering column and other loads associated with vehicle usage and effectively distribute the loads to the cross-car structural beam for distribution to the side walls of the vehicle.
In addition to compensating for the various loads of the steering column, the steering column structural support must accommodate for a first natural frequency and the undesirable effects thereof. The first natural frequency is a vibratory level of the vehicle structural system which, when reached, can result in undesired vertical oscillatory displacement of the steering column within the vehicle.
The steering column structural support in combination with the cross-car structural beam are typically relied upon in vehicle structural systems to prevent the occurrence of such displacement. This is accomplished by designing the structural support and the structural beam to increase the first natural frequency beyond a level anticipated to be reached during various vehicle operating modes. Additional mass and materials are added to the structural support and structural beam in order to control the occurrence of the first natural frequency.
Where the steering column is directly coupled with the cross-car structural beam, the various loads and the first natural frequency must be accounted for by the means of direct attachment such as nuts, bolts, welding, etc.
Efficient load compensation and first natural frequency accommodation within the vehicle depends upon a proper attachment of the steering column to the cross-car structural beam.
Typically, the steering column structural support is mechanically attached at the first end to a load bearing area of the cross-car structural beam. The load bearing area is generally a portion of the cross-car structural beam and may be located, more specifically, at an underside of the beam. The steering column structural support is attached to the load bearing area by one or more threaded bolts and secured with fasteners such as nuts.
In the instance of direct attachment, where no steering column structural support is utilized, the steering column is typically directly attached to the load bearing area using one or more nut and bolt combinations.
The nut/bolt arrangement provides very localized points of attachment. The result is an inefficient transfer of the vehicle loads from the steering column to the cross-car structural beam and an insufficient attachment for accommodating the first natural frequency.
The load bearing area is often a part of the structural air duct. Light-weight air duct assemblies are composed of a molded plastic or a molded plastic composite and are mounted to the rigid cross-car structural beam. A metal-to-plastic interface between the nut/bolt arrangement and the air duct tends to degrade the plastic of the air duct. Hence, the overall attachment of the steering column and the cross-car structural beam is degraded. Thus, the use of extra parts, such as washers and the like, must be employed to preserve the plastic of the structural air duct.
The attachment of the steering column structural support and the cross-car structural beam using the nut/bolt arrangement must be performed manually and requires the handling of several parts and tools, thus valuable labor time is consumed and extra expense incurred.
Mechanical means of attachment, such as the nut/bolt arrangement, used in securing the steering column structural support to the cross-car structural beam constitute considerable localized mass within the vehicle. The mass of the mechanical attachment means must be compensated and accounted for in designing the vehicle and, particularly, the vehicle structural system.
Accordingly, it is desirable to have a structural attachment system for attaching a steering column to a cross-car structural beam that is light weight, simple to manufacture and assemble, provides an effective and efficient distribution of steering column loads, and prevents against occurrence of the first natural frequency.
According to the present invention, a structural attachment system is provided for attaching components to one another within a vehicle, for providing reinforcement in load bearing areas of the components, and for allowing effective distribution of loads within the vehicle.
The structural attachment system includes a first structural member and a vehicle component attached to one another by an attachment assembly.
In one exemplary embodiment of the present invention, the first and vehicle components are a structural air duct assembly and a steering column, respectively, and the attachment assembly is a steering column support unit.
The steering column support unit is a member which attaches the steering column to the structural air duct assembly at a load bearing area. The load bearing area is a portion of the structural air duct assembly which is subject to the steering column and the forces and loads associated therewith.
The steering column support unit includes mounting members for coupling with and supporting the steering column.
The steering column support unit also includes an attachment element for facilitating connection with the structural air duct assembly. The attachment element may be shaped and contoured to mate flush with the structural air duct assembly at the load bearing area.
The steering column support unit may be made of plastic or metal or any material sufficient for the purposes within the scope of the present invention.
The steering column support unit may be attached to the structural air duct assembly by any sufficient method including, but not limited to, mechanical attachment, chemical attachment, or thermal attachment (e.g., vibration or sonic welding), etc. Alternatively, the steering column support unit may be formed integrally with the structural air duct assembly by, for example, compression molding.
The steering column support unit may include reinforcing elements to provide added load bearing ability and rigidity to specified portions of the unit. The reinforcing elements include fibers disposed within the material forming steering column support unit. The fibers may be carbon. The fibers are selectively included in a binder used to form the steering column support unit. The binder may be the same as that used in the formation of the structural air duct assembly thus facilitating integral formation of the assembly and the steering column support unit.
In another exemplary embodiment of the structural attachment system of the present invention, the first structural member and vehicle components are the structural air duct assembly and the steering column, respectively, and the attachment assembly includes a load plate assembly and a steering column support unit.
The load plate assembly mechanically attaches the structural air duct assembly and the steering column support unit, the steering column support unit being coupled with the steering column.
In this embodiment, the load plate assembly is disposed within a plurality of structural ribs which are formed as part of the structural air duct assembly. The structural ribs provide a structure which disperses the load received by the load plate assembly due to the nesting thereof within the structural ribs.
The load plate is formed of a material which is designed to receive and transfer loads and forces associated with the steering column. Preferably, the load plate is formed of a metal.
The load plate assembly includes a plate member. The plate member is disposed within the structural air duct assembly at the ribs.
The plate member has a plurality of openings formed therein and a number of fastener members are formed above the plurality of openings. The fastener members are designed to engage and mate with an equal number of fasteners.
Fasteners extend through the steering column support unit and through the structural air duct assembly to mate with the fastener members. Fasteners provide secure attachment of the steering column support unit to the structural air duct assembly.
In another embodiment of the load plate assembly, the plate member does not have a number of fastener members formed as part thereof but rather has a number of fasteners which extend therefrom.
In this embodiment, fasteners are connected to a bottom surface of the load plate and extend therefrom. The load plate, again, is seated within the structural air duct assembly at the ribs. The fasteners extend from the structural air duct assembly and pass through the steering column support unit. The fastener members attach the steering column unit to the fasteners and hence the unit is mechanically attached to the structural air duct assembly by compression caused by the load bearing assembly.
The structural attachment system of the present invention, provides for the attachment of various vehicle components and distributes loads and forces associated with the components throughout the vehicle structural support system.
In one embodiment, the structural system utilizes a steering column support unit with to attach a steering column and a structural air duct assembly. In another embodiment, the structural system utilizes a load plate assembly in conjunction with a steering column support unit to attach the steering column to the structural air duct assembly.
The various embodiments of the present invention described attach and support the steering column, reinforce a load bearing area of the structural air duct assembly, regulate vertical oscillatory motion of the steering column, and distribute the loads of the steering column across the structural air duct assembly and elsewhere throughout the vehicle.
The structural attachment system of the present invention provides for a vehicle structural system of reduced mass. Particularly, light-weight materials such as plastic may be used to form the vehicle components due to the added support and rigidity provided at the load bearing area by the steering column unit and/or the load plate.
The assembly described herein reduces extra parts need for assembly and provides a simplistic design allowing for ease of installation.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.